Ariel and Prince Eric are living a happily married life on land in Eric's kingdom. A new threat however surfaces in the form of Ursula's wicked sister, Morgana, and to protect their daughter, Melody, Ariel and Eric conceal the child's mermaid heritage. Unfortunately, Melody is as curious and head-strong as her mother and ventures into the sea against her parent's wishes. To prevent her daughter from becoming a pawn in Morgana's quest for Triton's kingdom, Ariel returns to the sea and reunites with her old friends Sebastian, Flounder and Scuttle.